There is a huge recruitment drive & a massive response to the vacancies, so probably minor mistakes may cause a rejection unfortunately. Things like poor grammar or not fulfilling the criteria exactly may be a cause.
The TOCs don't like the idea of people saying they will relocate, as many don't actually move & just drive in which will have big effects on their fatigue.
There's going to be a big recruitment drive for conductors now, Chester & Cardiff are already advertising. If people don't make it as a conductor maybe try as a conductor, as it's a great way to get on the railway & gives people a better understanding of how the railways work plus they can have an advantage with internal applications in the future
Only the HR department can answer this question, but it may be that there more people that don't have to relocate.
They can be very picky with so many people applying & it may be just a minor reason other than the relocation issue. Maybe try for conductors roles that have just been advertised